Would Gravity Exist Without Inertia?

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    Gravity Inertia
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Discussion Overview

The discussion centers around the relationship between gravity and inertia, particularly in the context of General Relativity (GR). Participants explore hypothetical scenarios where all motion ceases and the implications for gravity and time in such a situation.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • One participant proposes that if everything in the universe stopped moving, gravity would not exist, suggesting that gravity is merely a distortion of spacetime rather than a force of attraction.
  • Another participant counters that the premise is flawed because motion is relative, and gravitational interactions would still occur regardless of the state of motion of an observer.
  • A different viewpoint emphasizes that even if spatial motion ceases, time continues to progress, indicating that GR involves both space and time.
  • One participant asserts that if all motion stopped, the concept of time would not exist, questioning the applicability of GR in such a scenario.
  • Another participant challenges the notion that time can exist independently of motion, arguing that GR encompasses both space and time, and that elapsed time is observer-dependent.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between gravity, inertia, and the nature of time. There is no consensus on the implications of a hypothetical scenario where all motion ceases, and the discussion remains unresolved.

Contextual Notes

Some statements reflect personal interpretations and speculative reasoning rather than established scientific consensus. The discussion includes assumptions about the nature of time and motion that are not universally accepted.

Tiago
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Hello,

Let me explain my question. We know from GR, that gravity is just something (planet, light, etc) following a geodesic path through distorted spacetime. But that's just because everything is still in motion from the big bang, traveling at the speed of its own inertia.

So let's assume, just for the sake of argument, that EVERYTHING in the universe stopped moving. Impossible of course, but if that were to be true, planets and stars wouldn't just fall to each other because of gravity, right? Gravity wouldn't exist. We would probably stay in the ground, but feeling weightless, right? Gravity is not a force of attraction, just a distortion of our path through spacetime.

Is this correct?

Thanks
 
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No, sorry, it is not correct. Since motion is only meaningful relatively, between two objects, the premise itself is wrong: you're already motionless with respect to the Earth, which doesn't impact your gravitational interaction.
 
Even if you stop moving through space you are still moving through time. Remember, GR is about curved spacetime, not just curved space.
 
Tiago said:
Hello,

Let me explain my question. We know from GR, that gravity is just something (planet, light, etc) following a geodesic path through distorted spacetime. But that's just because everything is still in motion from the big bang, traveling at the speed of its own inertia.

So let's assume, just for the sake of argument, that EVERYTHING in the universe stopped moving. Impossible of course, but if that were to be true, planets and stars wouldn't just fall to each other because of gravity, right? Gravity wouldn't exist. We would probably stay in the ground, but feeling weightless, right? Gravity is not a force of attraction, just a distortion of our path through spacetime.

Is this correct?

Thanks
Hmmm. If everything stopped moving, I daresay there is no such thing as time. GR assumes time, so it does not apply in such a situation.
 
Hornbein said:
Hmmm. If everything stopped moving, I daresay there is no such thing as time. GR assumes time, so it does not apply in such a situation.
This is pure speculation and has absolutely nothing to do with real science. The correct answer has already been given. Please do not reply to post with speculation when you do not know the answer.
 
Times always tick(always exist) even if one could travel the speed of light. It is space that bends.
 
Legolaz said:
Times always tick(always exist) even if one could travel the speed of light. It is space that bends.
This is also not true. General relativity deals with curved space-time. Both space and time are involved in this. For any observer, elapsed time can always be computed by computing the proper time. In GR there is no such thing as a universal time.

Since this thread has started to attract responses with personal interpretations seemingly based on nothing but popularised science and the OP has been answered, I am closing it.
 

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